The long-term goal of this project remains the development of new agents for the treatment of human cancers. Since most, if not all, of the nucleosides currently in use for the treatment of human cancers must phosphorylated to their active forms, we plan to investigate in some detail the enzymes that are known to carry out this activation. Deoxycytidine kinase is the primary, but not the only, enzyme that initiates this activation process, so we plan to focus on it, in collaboration with Dr. Donna S. Shewach of the University of michigan. We plan to prepare a broad series of compounds with a focus on them activating enzymes as well as their antitumor selectivity. We also plan to examine our collection of nucleoside triphosphates as inhibitors of telomerase, a DNA polymerase which is activated in human cancers. The studies will show triphosphates we have on hand or easily generate, and will provide us with SAR information that will be used in designing new compounds that will be more specific inhibitors for this enzyme, which appears to be an important new target for can chemotherapy.